Production of electrotypes.



. PATENTED MAR. 10 1908. s. -0'. GOWPER-GOLES. PRODUCTION OFELEGTROTYPES.

A1 PLIOATION TILED FEB. 25, 1907.

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WZZILeS-Sf. 916%. a [9 m divided SHERARD OSBORN PRODUCTION OFELECTROTYPES.

COWPER-GOLES, OF LONDON, ENGLAND.-

Specification of Letters Patent.

Patented March 10, 1908.

, Application-filed February 25, 1907. Serial No. 359,298.

To all whom it may concern.-

Be it known that I, SHERARD OsBonN' .CowPER-CoLEs, a subject. of theKing of at Grosvenor Manestmlnster, London, new and useful Im- G rreatBritain, residin slons, Victoria street, England, have inventedprovements in the Production of Electrotypes; and .do hereby declarethat the followlng is a full, clear, and exact descriptlon of the same,which will enable others skilled in the art to which it appertains tomake and use the same. This invention relates to improvements in theproduction ofelectrotypes for the manufacture of plates for printingpurposes.

It'hasheretofore been the general practice, when 1t is desired toproduce or reproduce an engraved copper plate, to make a wax mold orimpresslon of the original plate and to then render, the surface of themold or impressloncapable of conducting electricity by coatlng 1t withbronze powder or plumbago, copper being subsequently electro-depositedupon thlS prepared surface until the desired thickness of deposit isobtained. This process possesses the disadvantage of being comparatlvelyslow and tedious and, owing to the low. electrical conductivity of thesurfaceupon which the deposit'is made, a conslderable tlme is occupiedby the copper in spreading over the whole of the surface,

this being the case evenwhen auxiliary means are employed foraccelerating the first covermg of the mold, such for example as brushlngthe surface over with finely iron which becomes coated with copper whenlmmersed in a suitable copper solution. It has also been proposed tomake moldsor matrices by impressing the original block Into soft metal,such as lead, this being effected by pressing a lead sheet on to theblock from which the" impression is to be made through the medium of agrooved iron plate,

a sheet of soft or elastic rubber being Introduced between the groovediron plate and the lead sheet.

Now, my invention has. for its object to improve the existingprocesses-and; to this .end I make use of a lead sheet with the soft orelast1c backing as above'described and I place upon the said soft orelastic backing a 1 whole. being l ilelld second piece of lead,thetogether by means of lead rivets. block or surface tobe reproduced andthe ing an im ression by the block to prepared leadare then subjected toconsidernicety and such that it cannot be distinguished from theoriginal.

Any suitable depositing apparatus may be employed such, for example, asthose described in the specifications of my former English patents Nos.13012/04, 15762/06 and 4668/05.

To enable the invention to be fully understood I will describe it byreference to the accompanying drawing in which Figure 1 is a perspectiveview of a lead plate prepared in accordance with the'lnvention. -F1g. 2is a similar view to Fig). 1 showe reproduced an also showing the secondbacking, extended beyond the edges of the elastic backing.

.a is the lead sheet or pressed by the block to late which is imereproduced, for

.mstance as shown at b in Fig. 2, and c is the soft or elastic backingplaced behind the platea. dis the second piece of lead placed in contactwith the elastic backing c and e e are the rivets for holding the saidparts a, c and (1 together.

I 3 Having now particularly described and ascertained the nature of mysaid invention and in what manner the same is to be performed, I declarethat what I claim is 1. A matrix comprising a lead sheet, anintermediate layer of elastic material and a backing of soft material,"substantially as described. Y

2. A matrix comifising a sheet of lead g of elastic material,

provided with a bat and a second sheet of lead placedon theelasticbacking, substantially as described.

SHERARD OSBORN COWPER-COLES. Witnesses:

JOHN E. BONSFIELD,-' A. ALBUTT.

